Multi-Technology Approach to Motor Management. Technology Approach to Motor Management

Transcription

1 MultiTechnology Approach to Motor Management Dr. Howard W. Penrose, Ph.D. General Manager, ATEST Pro A Division of BJM Corp Old Saybrook,, CT In this presentation, we shall cover how to create success using a Multi Technology Approach to Motor Management BJM Corp is a submersible pump and motor test equipment manufacturer. Established in 1983, BJM introduced the first motor circuit analysis instruments in The instruments are handheld, simple to use and cost effective showing immediate ROI s in virtually any application. Dr. Howard W. Penrose is the General Manager of BJM Corp s ATEST Pro Division with 20 years in the electric motor system industry from motor repair to advanced research in electric motor systems. 1

2 Presentation Overview What is a Motor System? Technology and Component Fault Detection System Breakdown Faults and Detection Common Approaches Case Studies Return on Investment Considerations for Selection Application Opportunities ATEST Pro Equipment The overall presentation shall include: Defining the motor system What equipment is used to detect what kind of motor system component faults A breakdown of each motor system component and what is used for fault detection. Common approaches to using multiple technologies in motor systems Which are the best combinations Several multitechnology case studies A return on investment example Additional considerations for selection of equipment to diagnose motor systems. Motor system application opportunities An overview of ATEST Pro instruments and software for motor management 2

3 What is a Motor System? The Electric Motor System ThreePhase Input Power Process Mechanical and Electrical Feedback Motor/Drive Subsystem Mechanical Subsystem 1200 rpm The motor system includes the power distribution system; the motor starting, control, and drive system; the motor; the mechanical coupling; the mechanical load; and the process. The facility power distribution system includes components such as inplant wiring and transformers. The starting, control, and drive system includes the motor starter and adjustable speed drives. The motor itself in this outline is an induction motor. The mechanical coupling refers to components like vbelts and power transmission devices. The mechanical load refers to the driven equipment, such as a pump, fan, compressor, or conveyor. The process is what is being accomplished, such as water pumping, mixing, or aeration. Most users look at motor systems from the component level and try to evaluate or troubleshoot. The systems approach is a way of looking at the reliability of the entire system and the relationship and synergy of the components. 3

4 Motor System Diagnostic Technology Comparison PQ Cntrl Conn Cable Stator Rotor Air Gap Brgs Ins Vibe Align oad VFD Offine Testing High Potential Testing Surge Test Insulation Tester Ohm Meter PI Testing MCA Test Onine Testing Vibration Analysis Infrared Ultrasonics Volt/Amp MCSA = Yes; = ate stage faults/imited detection; = No This table represents each of the common technologies used to evaluate components within an electric motor system and their common test capabilities. Note, for instance, that high potential testing, insulation to ground testing and polarization index testing each only evaluate the insulation system and must be performed with the equipment deenergized. Surge testing can only evaluate the first couple of turns into the stator windings and an ohm or milliohm meter can only detect severe or latestage winding faults or poor connections. Both high potential and surge testing are potentially harmful to the health of the motor should there be any issues such as aged insulation or contamination. Motor circuit analysis provides a more definitive view of these components, and more. The online tests can provide a broader view of the overall system, assuming the system is able to operate. When the motor system is viewed, overall, motor current signature analysis provides a broader overview with only a few limitations. Aside from an overview of component test ability, a few more things need to be considered 4

5 Management Considerations Test Method Estimated Pricing Non Destructive Requires Experience Dedicated Personnel Included Software Other Applications Offine Test High Potential $10,000 + Potentially Destructive High Recommend No No Surge Test $25,000 + Potentially Destructive High Recommend Some No Insulation Tester $1,000 + (NDT) Non Destructive Some No No Yes Ohm Meter $500 + (NDT) Some No No Yes PI Tester $2,500 + (NDT) Medium No Some No MCA $1,000/ $9,000 + (NDT) Some No Yes Yes Onine Test Vibration $10,000 + (NDT) High Recommend Yes Yes Infrared $10,000 + (NDT) High Recommend Yes Yes Ultrasonics $10,000 + (NDT) High Recommend Some Yes Volt/Amp $500 + (NDT) Some No No Yes MCSA $16,000 + (NDT) High Recommend Yes Yes A few additional considerations have to be reviewed by managers prior to obtaining motor system diagnostic equipment: What is the general cost for the equipment? Note that the costs presented here are estimates. Is the equipment potentially destructive or nondestructive. For the purpose of this demonstration any instrument that can potentially change the operating condition of the equipment through misapplication or finishoff weakened conditions shall be considered potentially destructive. How much experience is required to operate the equipment? Does it require a specific discipline? Does the equipment and software require dedicated personnel in order to get full use of it? Does it include software? How much training is required? Can the instrument be used to test equipment other than motor systems? 5

6 Incoming Power Power Quality Harmonics (Voltage and Current) Over/Under Voltage Voltage Unbalance Power Factor Overload Detected With MCSA imited with Voltmeter and Ampmeters The first area of the motor systems potential reliability issues is power quality. The most common problems include: Voltage and current harmonics. Current is potentially the most harmful. Over and undervoltage conditions. Electric motors are designed to operate no more than 10% high or low from the motor nameplate value. The preferred range is +/ 5% of the nameplate value. Voltage unbalance is the difference between phases. The relationship between voltage and current ranges from a few times to many times current unbalance as related to voltage unbalance based on motor design (can be as high as 20 times). Power factor of the system. The lower the power factor from unity, the more current the system must use to perform work. Overloaded system based upon capabilities of the transformer, cabling and motor detected as current related to nameplate values. Each of these problems can be easily detected using voltage and currentbased motor current signature analyzers. Volt and Ampmeters provide limited capability to detect problems. 6

7 Transformer Faults Insulation to Ground Winding Shorts oose Connections Electrical Vibration Test Equipment MCSA MCA Infrared Analysis Insulation Tester Ultrasonics Transformers Transformers are one of the first critical components of the motor system. In general, transformers have fewer issues than other components of the motor system. However, one transformer usually takes care of multiple systems both in the electric motor as well as other systems. Common transformer problems include: Insulation to ground faults. Shorted windings. oose connections, and, Electrical vibration Test equipment for evaluating the condition of transformers include: Motor current signature analysis Motor circuit analysis for grounds and shorts Infrared analysis for loose connections Ultrasonics for looseness and severe faults Insulation tester for insulation to ground faults 7

8 MCC Controls and Disconnects MCC/Disconnect Problems oose Connections Bad Contacts Bad Coils Bad PF Correction Capacitors Test Methods MCSA MCA Infrared Ultrasonics Volt/Amp Meter Ohm Meter Visual The motor control or disconnect provides some of the primary causes of motor system problems. The most common for both medium and low voltage systems are as follows: oose connections Bad contacts including pitted, damaged or worn. Bad starter coils Bad power factor correction capacitors The test methods for evaluating the control systems are fairly numerous with MCA, Infrared and MCSA providing the most accurate evaluations. 8

9 Cables (Before and After Controls) Cable Faults Thermal Breakdown Contamination Shorts and Grounds Open Physical Damage Test Instruments MCA MCSA Infrared Insulation Tester System cabling problems are rarely considered and, as a result, provide some of the biggest headaches. Common cable problems include: Thermal breakdown due to overloads or age. Contamination which can be even more serious in cables that pass underground through conduit. Phase shorts can occur as well as grounds. These can be caused by treeing or physical damage. Opens due to physical damage or other causes. Physical damage is often a problem in combination with other cable problems. Test instruments include motor circuit analysis, motor current signature analysis, infrared and insulation to ground testing. 9

10 Electrical Distribution System TuneUp Improving inplant electric power distribution systems Undersized Conductor (10%) Poor Connections (36%) Voltage Unbalance (7%) Voltage Deviation (2%) Mismatched Voltage (6%) Poor Power Factor (39%) Problems in the system before the electric motor can be broken down in the following order: Poor power factor Poor connections Undersized conductors Voltage unbalance Under or over voltage conditions The most common equipment that covers all of these include motor circuit analysis, motor current signature analysis and infrared analysis. 10

11 Mechanical Faults Bearings Bad Shaft/Brg Housing Vibration Mech Fault Testing MCSA Vibration Infrared Ultrasonics Electric Motor Electric motors include mechanical and electrical components. The first review is mechanical. The primary mechanical problems include: Bearings Bad or worn shaft or bearing housings Vibration issues Each of these can be detected using: Motor current signature analysis will detect the more severe problems. Vibration analysis will detect the faults earliest but requires a fair amount of experience. Infrared will detect problems when they are severe. Ultrasonics will detect the more severe problems 11

12 Electric Motor Electrical Faults Winding Shorts Insulation to Ground Contamination Rotor Faults Air Gap Faults Winding Tests MCA MCSA Vibration Megger HiPot, Surge Test OhmMeter Volt/Amp Meters Ultrasonics Infrared Electrical faults include: Winding shorts including turn to turn and coil to coil Insulation to ground faults Winding contamination Rotor faults including casting voids and broken rotor bars Air gap faults including an eccentric rotor The winding tests to detect these problems include: MCA and MCSA will detect all of the faults Vibration will detect latestage faults Insulation to ground will only detect ground faults Surge testing will only detect winding shorts in the first few turns of the winding All other testing will only detect late stage faults. 12

13 Coupling (Direct and Belted) Faults Misalignment Belt/Insert Wear Tension Issues Sheave Wear Test Instruments MCSA Vibration Infrared The coupling between the motor and load also has faults due to wear and application: Belt or direct drive misalignment Belt or insert wear Belt tension issues are more common than most think and usually result in bearing failure. Sheave wear The most accurate system for fault detection is vibration analysis then motor current signature analysis then infrared analysis. 13

14 oad (Fans, Pumps, Compressors, Gearboxes, Etc.) oad Faults Worn parts (ie( ie: : seals) Broken components (gears, fan or impellor blades, etc.) Bearings, etc. Test Instruments MCSA Vibration Infrared Ultrasonics The load can have numerous types of faults depending upon the type of load. The most common are: Worn parts Broken components Bearings Test instruments capable of testing load problems include: MCSA Vibration Infrared Analysis, and Ultrasonics 14

15 Common Approaches PQ Cntrl Conn Cable Stator Rotor Air Gap Brgs Ins Vibe Align oad VFD Insulation Resistance and PI Infrared and Vibration Surge and HiPot MCA and MCSA MCA and Infrared / Vibe Many select mechanical approach (vibe and infrared) if applying a reliability program. Most use Insulation and PI testing with limited results New approach has been a combination of the MCA and/ or MCSA with a vibration and infrared program for multitechnology technology approach to confirm findings. Uses combination of electrical and mechanical. cal. There are several common approaches within industry and several new approaches. The best use a combination of energized and deenergized testing. It is important to note that energized testing is usually best under constant load and trended in the same operating conditions each time. One of the most common approaches has been the use of insulation resistance and/or polarization index. These will only identify insulation to ground faults in both the motor and cable, which represent under 1% of the overall motor system faults (~5% of motor faults). Infrared and vibration are normally used in conjunction with each other with great success. However, they miss a few common problems or will only detect them in the late stages of failure. Surge testing and high potential testing will only detect some winding faults and insulation to ground problems. The following two approaches have become more common over the past decade: Motor circuit analysis and motor current signature analysis support each other and detect virtually all of the problems in the motor system. This accuracy requires MCA systems that use resistance, impedance, inductance, phase angle, current/frequency response and insulation to ground and MCSA systems that include voltage and current demodulation. The most common approach is vibration, infrared and motor circuit analysis. The strength of this approach is that there is a combination of electrical and mechanical disciplines involved in evaluation and troubleshooting. As found in the motor diagnostic and motor health study, 38% of motor system testing involving only vibration and/or infrared see a return on investment. This number jumped to 100% in systems that used motor circuit analysis along with vibration and/or infrared. 15

16 Surge Test Ohm Meter PI Testing MCA Test Vibration Analysis Infrared Ultrasonics Volt/Amp MCSA Test Method High Potential Testing Insulation Tester Final Considerations Where Can You Test At Motor Requires disconnect At Motor Requires disconnect From MCC At Motor Requires disconnect At Motor Disconnect Recommended From MCC At each location tested At each location tested At each location tested From MCC From MCC Example of Difference: Testing 20 motors at one site took just over an hour During a survey using MCA testing. Same motors required testing over entire Day using vibration analysis during same survey. A final consideration when reviewing the systems to use as part of your motor system evaluation is where you have to test and the time involved. For instance, during the PG&E electric motor performance analysis tool study, MCA testing was performed from a motor control center and results found. Vibration analysis on the same motors required the day as testing required traveling to each location. High potential testing, polarization index and surge testing should be performed at the motor with all cabling disconnected. Insulation testing, motor circuit analysis, motor current signature analysis and volt/amp testing can each be performed from the MCC. All of the other tests are usually performed at each location being tested. Is this bad? Not really, one of the benefits of testing at each location is the ability to identify visual problems. 16

17 400 HP Fault at Steel Mill High electrical vibration that increases as the motor heats up In this first case study, a problem in a 400 horsepower electric motor at a steel mill was identified. This problem had been driving the maintenance and reliability group crazy for about two months. As it was part of a parallel system, this motor was used only as a backup, which created another problem an unreliable back up system. The motor had an electrical vibration that showed some looseness, when the motor was energized. The vibration would continue to increase as the motor s operating temperature increased. The signature would disappear when deenergized. The bearings had been replaced and a number of other symptoms were addressed to no avail. As a highfrequency signature in vibration looked like rotor bars, which were known, with multiple harmonics, it was determined that the fault must be a rotor problem. The motor was sent to a local repair shop who happened to have MCA equipment. The rotor and stator were tested. 17

18 Test Results Winding Test Rotor Test Resistance Impedance Inductance Phase Angle I/F Insulation T1T T1T #.# T2T T1 T2 T3 As you can see from these readings, the stator winding was in excellent health. The rotor shows a few flat spots in the waveform and a slight arch as you go right to left. These findings indicate small casting voids in the rotor and that there is a little rotor eccentricity. However, neither of these findings indicate a problem as severe as what was being seen. Time to test, including rotor test: <30 minutes. 18

19 Findings If all of the least likely problems are eliminated, what remains, however improbable, is the fault. In this case, a single pin from the bottom of the stator housing holds the stator core in place. There are no welds, as they would break during thermal growth. However, the stator was not completely tight within the stator housing and both the stator housing and core are made of two different materials. It appears that the stator housing was growing faster than the stator core, causing the vibration and looseness. Marks on the core and stator housing ribs proved the indication (as well as a slightly visible spacing). You will note balancing weights on the second picture. As an interesting tidbit of knowledge, significant casting voids, because they are missing metal, can usually be found right behind balancing weights on the rotor. 19

20 Infrared, Vibration and MCA : During a routine IR predictive maintenance route a thermographer determined a motor was operating at an excessive temperature. The motor in question was a 7.5 horsepower coolant pump in a transmission case machining center and, due to its location, additional analysis with IR was difficult. The machining center involved is responsible for critical machining on a key component in the assembly plant. If the cooling pump failed, history revealed that the loss of production would result in assembly plant shutdown. A work order for additional analysis was produced to determine if the trouble was electrical or mechanical. The motor and cabling tested electrically good with motor circuit testing. A bearing fault was detected, using vibration analysis, and a repair versus replace decision was made. The coolant pump motor was replaced during routine downtime and a followup IR scan showed the motor operating within normal parameters. 20

21 Infrared and MCA During another routine IR predictive maintenance route, the thermographer identified a critical machine tool motor with a nonspecific high stator temperature. The drilling machine was a bottleneck for one process line where it drilled four mounting holes in transmission cases. oss of the critical motor would shut down the process line. A replacement motor was identified with an estimated three day delivery time. Motor Circuit Analysis was performed and a nonparallel impedance and inductance reading identified winding contamination while an insulation to ground test showed a high MegOhm reading. The electric motor was pulled and sent into an electric motor repair shop for repair and investigation as part of a routecauseanalysis. The motor repair shop discovered fluid in the motor housing, poured a sample and analysis found it to be a mixture of coolant and hydraulic oil. The motor winding was cleaned, dipped and baked, a motor seal replaced, and the leak on the machine tool found and repaired with a turnaround time of less than 24 hours from detection of the problem. If left, the motor would have suffered a catastrophic winding failure most likely resulting in a loss of at least 72 hours production time. 21

22 Example of Starter Problem Operation Stops Checked motor from Starter Discover Starter Problem Fault: Poor Contact; Motor OK Fault not visible Checked and found motor and Cable OK An electric motor trips off line. During the setup to check the electric motor from a starter, a starter fault is detected. The contacts are checked in the starter and the B phase contacts appear to have exploded. As it turns out, the motor was tested and found to be, electrically, in good condition. The fault was determined to be the result of arcing in the contacts, most likely due to a loose contact. The starter was replaced and the equipment put back in operation. 22

23 Financial Impact Traditional Technologies: IR, Vibe, Ultrasonics Introduced MCA Jan02 Feb02 Mar 02 Apr 02 May02 Jun02 Jul 02 Aug02 Sep02 Oct02 Nov02 Dec Cost Avoidance: $307,000 in Maintenance Costs Alone Does not include production cost avoidance. What is the financial impact of a combination of infrared, vibration and motor circuit analysis? In this example, taken from a Midwestern automotive manufacturer, up through September, 2002, findings using infrared, vibration and ultrasonics provided good results. The application of motor circuit analysis, using an A TEST IV PRO 2000, resulted in an increase in maintenance direct cost avoidance of $307,000, which does not include production cost avoidance. 23

24 Application Opportunities Commissioning Troubleshooting Trending Evaluating equipment before Installation at Vermont Yankee Nuclear station There are three common opportunities for electric motor system testing. These include: Commissioning components or the complete system as it is newly installed or repaired. This can usually provide a very immediate payback for the technologies involved. Troubleshooting the system. Through the proper application of multipletechnologies, problems can be identified and corrected rapidly. Trending of test results for system reliability, again using the proper application of multipletechnologies. Using tests such as motor circuit analysis and vibration analysis, potential faults can be trended over the long term, detecting some faults months in advance. 24

25 ATEST Pro Solutions for Motor Diagnostics Instrument Solutions ATEST III ATEST IV PRO 2000 ATEST Pro O Software Solutions Condition Calculator 2.0 Condition Calculator PPC TREND 2003 EMCAT Kit Solutions ATEST Professional ATEST Pro MD ATEST Pro provides multiple solutions to meet MCA and MCSA needs: The ATEST III MCA troubleshooting tool The ATEST IV PRO 2000 handheld motor diagnostic instrument The ATEST PRO O handheld motor current signature analysis instrument With the associated software: Condition Calculator 2.0 and Condition Calculator PPC for the ATEST III The TREND 2003, which comes standard with the ATEST IV PRO 2000 And the EMCAT option for advanced motor and transformer management programs. There are several kit solutions: The ATEST Professional kit includes the ATEST III, ATEST IV PRO 2000, a training motor, EMCAT software, DC test fixtures and the Motor Circuit Analysis book, and The ATEST Pro MD, the complete solution for motor health, which includes the ATEST Professional kit as well as the ATEST Pro O and two days of training on motor management programs. Each of the instruments are simple to use, handheld and provide immediate and definitive answers. 25

26 BJM Corp, ATEST Pro 123 Spencer Plains Rd Old Saybrook,, CT To obtain additional information on motor diagnostic technologies, applications and more, contact: ATEST Pro, a Division of BJM Corp 123 Spencer Plain Rd Old Saybrook, CT Phone Fax: alltest@bjmcorp.com Web: Dr. Penrose can be reached via the above or hpenrose@bjmcorp.com Thank you for your time. 26